linux-kernel - Re: [PATCH 3/6][v5] Define siginfo_from_ancestor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090105143334.GD3313@redhat.com>
Date:	Mon, 5 Jan 2009 15:33:34 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Cc:	ebiederm@...ssion.com, roland@...hat.com, bastian@...di.eu.org,
	daniel@...ac.com, xemul@...nvz.org, containers@...ts.osdl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6][v5] Define siginfo_from_ancestor_ns()

Really minor nit, just noticed...

On 12/27, Sukadev Bhattiprolu wrote:
>
> +static inline int siginfo_from_ancestor_ns(struct task_struct *t,
> +                       siginfo_t *info)
> +{
> +	struct pid_namespace *ns;
> +
> +	/*
> +	 * Ensure signal is from user-space before checking pid namespace.
> +	 * (We maybe called from interrupt context and dereferencing
> +	 * pid namespace would be safe).
> +	 */
> +	if (siginfo_from_user(info)) {

I can't parse the comment above, and imho it is confusing and
misleading. We can dereference pid namespace even in interrupt
context.

Also, the comment looks as if "when siginfo_from_user() is false,
it is not safe/possible to derive from_ancestor_ns". This is not
true, in that case we know that from_ancestor_ns must be false.

from_ancestor_ns == T means the signal was sent from the user
space, and it was sent to the task in the sub-namespace, so it
is clear why we check siginfo_from_user().

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/